1 files changed, 3 insertions, 0 deletions
diff --git a/eval.c b/eval.c
index feac81024c..dcba1e16d0 100644
--- a/eval.c
+++ b/eval.c
@@ -1036,6 +1036,7 @@ rb_mod_include(int argc, VALUE *argv, VALUE module)
     CONST_ID(id_append_features, "append_features");
     CONST_ID(id_included, "included");
 
+    rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);
     for (i = 0; i < argc; i++)
 	Check_Type(argv[i], T_MODULE);
     while (argc--) {
@@ -1083,6 +1084,8 @@ rb_mod_prepend(int argc, VALUE *argv, VALUE module)
 
     CONST_ID(id_prepend_features, "prepend_features");
     CONST_ID(id_prepended, "prepended");
+
+    rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);
     for (i = 0; i < argc; i++)
 	Check_Type(argv[i], T_MODULE);
     while (argc--) {